Fix branch passing into IPA post job
Fix branch passing into IPA post job

BRANCH_PATH wasn't passed properly into this script, an export should
fix that.

Change-Id: I3875e041b2b9f67bbe41f35a4df63f232a4b272f

openstack-infra/project-config,dongwenjuan/project-config,dongwenjuan/project-config,Tesora/tesora-project-config,Tesora/tesora-project-config,openstack-infra/project-config